1. Field of the Invention
The present invention relates to a method of forming a metal trench pattern in a thin-film device and to a manufacturing method of a thin-film device.
2. Description of the Related Art
When manufacturing a thin-film device with a metal trench pattern such as a trench capacitor for example, in general, recesses or trenches are first formed and then an adjacent space layer is deposited on top surfaces around the recesses in order to self-align a height of a top surface of opening edges of the recesses with a height of the top surfaces of the adjacent spaces around the recesses. U.S. Pat. No. 6,207,524 B1 discloses such method for manufacturing a semiconductor memory cell with a trench capacitor.
However, if the deposition is done to form an adjacent space layer around recesses after forming these recesses, the layer will be also deposited in the recesses and the deposited layer once formed in the recesses will be difficult to completely remove. Particularly, in case that the trench is deep, it may be impossible to remove the deposited layer in the trench. If such unnecessary deposited layer is remained in the recesses, it may be impossible to keep a precise shape of the trench as desired. In such case, it will be difficult to fabricate, by utilizing the trench pattern, a trench capacitor with high precision and high quality.
To solve such problem in the conventional art, the assignee of the present application has proposed a method of forming a recess pattern in Japanese Patent Application No. 2007-089644, filed on Mar. 29, 2007. According to the proposed method, openings of a metal trench pattern are covered by a dry resist film to prevent an adjacent space layer from being deposited in the recesses. It should be noted that this Japanese Patent Application No. 2007-089644 had not published when the present invention was invented and also when the present application was filed.
However, according to this recess pattern forming method proposed by the assignee of the present application, since the dry resist film or resist pattern is removed just after the metal trench pattern is formed, the most part in the recesses is remained hollow during the following processes. This causes convex portions or pillars that form the trench there between to easily deform or to topple over, particularly when the trench is deep.